Method for loading a bore hole



May 28, 1963 c. E. GREBE 3,091,177

METHOD F' OR LOADING A BORE HOLE Filed Aug. ll. 1960 Fir/'ng /l'ne Semm/ng Exp/067V@ /000/ xp /os/Ve /000/ Exp/@sive /000/ 0/56 Dello/'millor INVENTOR. 0r/E. Grabe BY 06E N United States Patent O 3,091,177 METHOD FDR LOADING A. BORE HOLE Carl E. Grebe, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Aug. 11, 1960, Ser. No. 49,017 Claims. (Cl. 102-22) This invention is related to an improvement in explosives and more particularly is concerned with a process and device for upgrading the useful power and Work which can be obtained from `a given explosive load.

It is -a principal object of the present invention to provide a means of upgrading and increasing the useful work obtained from the energy released in an explosive blast.

It is another object of the present invention to provide a safe, easy to use method of controlling and directing explosive -blast energy.

-It is a further object of the present invention to provide a means of increasing the effective rock breakage in a mine or quarry blast that can be realized from a given amount of an explosive material.

Still other objects and advantages will become apparent upon reading the detailed description presented hereinafter and by reference to the accompanying drawing.

An unexpected increase in the effective work of a given explosive coupled with lateral directionalization of the blast energy is provided by the method of the present invention wherein non-structural, substantially circular members are placed laterally at intervals throughout the length of the explosive load in a manner substantially the same as that shown in the drawings.

FIGURE 1 presents a sectional view of one embodiment `of a bore hole loaded with an explosive and containing a series of saucer-shaped circular discs spaced at intervals throughout the length of the load, each disc delining a center opening.

FIGURE 2 is a'view taken along line 2 2 of FIG- URE 1.

In utilizing the present means of upgrading the eiective work obtainable from a given explosive substantially in cylindrical form, as is found in a loaded bore hole for example, `generally the members used will have one circular plane and preferably will define openings for passing explosive therethrough. Further, these members will have a maximum diameter about the same as that of the cylindrical explosive form. These members need not be hat circular discs but can be dish-like, a segment of an oblate spheroid, pyramidal, truncated conical, a hemisphere, a segment of `a prolate spheroid, t-runcat-ed pyramidal, a spherical segment and the like. In fact, in actual tests it has been shown that high eiective work powers and excellent directionalization of an explosive blast is obtained if the members are not ilat but have a sloping wall whereby they range in shape from that of a saucer to a true cone.

In any event, these members will be of such a thickness as to be nonstructurally conning of -an explosive blast. The actual thickness to be utilized for the members will vary depending on the type of explosive with which they are utilized, the number of members used within a given bore hole and the type of material from which they are constructed. Generally they will range in thickness from that of commercially available metal foil (about 0.001 inch) up to about 1 inch or more.

The members can be made from a variety of nonstructural materials, eg., glass, ceramic, resin, rubber, wood, metal, etc. Preferably they will be made of -an electron conducting material such as iron, zinc, magnesium, aluminum, titanium, zirconium and alloys there- 3,@9Ll77 Patented May 28, 1963 of and desirably they will be prepared from magnesium, aluminum, magnesium alloys or aluminum alloys. It is understood these members can be prepared -by any of a number of suitable conventional means, that is deep drawing, shaping, stamping, molding and casting.

In carrying out the method of the present invention, the members will be positioned laterally lat intervals along the principal axis of a cylindrical explosive load as in a bore hole and will have the plane of their maximum diameter parallel to the cross-sectional plane, as dened by the base or top of said cylindrical explosive load, for example, and will be normal to the principal axis of this load, and will be separated from each other by the explosive material. Ordinarily, the members will have a diameter slightly smaller than the diameter of the load, which will not only permit easy placement of these in a bore hole but which also will lend for ease in maintaining these members in a lateral position within the explosive 'load and bore hole. Members will be placed at spaced intervals ranging from about 4 inches to about 10 feet apart in a normal 20 to 40 foot deep explosive load within a bore hole. Preferably these will be spaced at a distance ranging from about l to about 6 feet apart. With magnesium or aluminum discs, for example, when utilized with an ammonium nitrate based explosive in taconite effective results have been found with the members being placed at from about 1 to about 3 foot intervals throughout the explosive load in a 9 inch diameter bore hole.

The actual procedure for loading of a bore hole utilizing these members will depend somewhat on the type of explosive used. For example, with a free owing granular explosive such as bulk dynamite, TNT, ammonium nitrate-fuel Oil and the like a disc containing an opening or perforations can be placed in the hole, a

v predetermined quantity of explosive then be poured in,

another disc placed on top of the explosive, more explosive then added and so on in alternate layers until the hole is loaded to the desired depth.

With a metallized explosive load such as a mixture utilizing coarse metal particles and a fluid form `of -ammonium nitrate, the cir-cular members can -be placed in a bore hole and be kept separated by the coarse metal particles used in the mix. The liquid explosive cornponent then can be poured over the metal in the hole.

The invention of the present application is further illustrated by the following examples but is not meant to be limited thereto.

Example 1 A 51/2 pound explosive load, comprised of aluminum sheet foil cones (14 percent by weight of the total explosive load), coarse magnesium ichips (14 percent of the weight of the total load) and 72 percent by weight of an aqueous aimmoniacal ammonium nitrate lsolution (containing about 5 percent by weight water, about 25 percent by weight ammonia, balance ammonium nitrate) was prepared in the following manner. A cylindrical canister `of about 6 inches in diameter and about 1 foot high was made f-rom aluminum foil. An yaluminum cone having a base of substantially this same diameter and defining lau opening at its apex -was placed in the bottom of the canister, a layer of coarse magnesium chips was added, another cone was then placed over the chips, and this procedure was continued until the canister was filled. The ammonium nitrate solution was then poured over the alternately layered aluminum cone-magnesium chip system and the so prepared load was placed in a 6 inch diameter, 6 feet deep bore hole drilled in sandstone. A shaped charge initiator was placed on top of the load and the remaining 5 feet of the hole was stemmed with sand. After permitting the load to stand for about 35 minutes, it was fired.

The shot produced an actual crater of about 9 feet in diameter but a humped and lifted up area about 30` feet in diameter was noted extending out from the `bore hole. This was an extremely effective shot when evaluated from the standpoint of work produced.

In a comparative shot, a load of the same composition was prepared in a similar canister. The metal used in this load was a 50-50 mixture by weight of coarse magnesium and coarse aluminum chips and no cones. This charge was loaded into a bore hole, armed and the hole stemmed `as described above. The explosion resulting upon detonation produced a crater `about 1l feet in diameter, but there was no evidence of any unusual humping of the ground surrounding this crater.

Example 2 A 51/2 pound explosive load containing 20 percent by weight aluminum (flat discs `of about 6 inch diameter), 20 percent by weight coarse magnesium chips and 60 percent by weight of the ammonium nitrate solution of composition as used in Example 1 was prepared in a 6 inch diameter by 1 foot long aluminum foil cylindrical canister. The aluminum discs were placed laterally throughout the length of the canister and were separated by alternate layers of the Imagnesium chips. The load was placed in a 6 inch diameter 6 feet deep bore hole, armed with a shaped charged placed on top of the load, the hole stemmed with about feet of sand and the explosive detonated. A crater about 111/2 feet in diameter and about 5 feet deep resulted, with evidence of some additional explosive Work being manifested beyond the periphery of the crater.

In `a comparative shot, a load of `this same composition, but using scrap magnesium and aluminum chips was fired in a similar manner. A crater of about 11 feet diameter was formed which was not `as deep as that produced when the flat discs were used in the explosive load.

Example 3 A 51/2 pound explosive load consisting of 6 perforated, at magnesium alloy die cast discs (2() percent by weight of total mix), a mixture of coarse magnesium-aluminum machine chips percent by weight of total mix) and 60 percent of ammonium nitrate solution of composition as used in Example 1, was prepared in a polyethylene bag. Alternate layers of the discs (each of which was about 71/2 inches in diameter and about 0.12 inch thick) and the machine chips were built up in the bag. The solution was then poured over the resulting metal structure. The load was armed with a shaped charge and placed in an 8 inch diameter bore hole about 5 feet deep in sandstone. The hole was stemmed with sand red.

The resulting explosion produced a crater about 12 feet in diameter with a total area of humping of about 16 feet diameter. Additionally, this shot was found to be of high velocity.

Example 4 A comparative set of shots was run in a series of commerical bore holes drilled in taconite. One set of holes was loaded with metal (S0-50 magnesium and aluminum) comprising about 40 percent by weight of the total explosive load. These metal chips were used to form alternate layers with saucer-like perforated magnesium discs defining a center opening. The discs were placed at 3 feet intervals up through the bore hole. A liquid ammoniacal solution of ammonium nitrate, composition as described in Example 1, was poured over the metal in the hole, this solution comprising about 60 percent by weight of the explosive load and just covering the metal.

In 'a second series of bore holes, a similar explosive composition was prepared but the metal was all coarse magnesium and aluminum chips.

Each of the holes was armed with a shaped charge placed :on top of the load and stemmed with drill cuttings.

Upon detonation of the holes containing the discs, a heaving action of the rock was noticed and there was a tremendous lateral movement of readily shovelable rock outward from the bench face.

Detonation of the holes containing the metal chips alone gave good rock breakage, but produced substantially no lateral movement of rock out from the face of the ore bed.

In a manner similar to that described for the foregoing examples, thin iron hemispheres placed at about 6 feet intervals throughout the length of a load `of free iiowing dynamite in a bore hole of limestone can effectively directionalize and lateralize the explosive blast resulting therefrom. Zinc truncated pyramidal members placed at about 10 feet intervals throughout the length of a load `or TNT in 'a bore hole can upgrade the explosive force resulting therefrom. Perforated pie pan shaped titanium discs placed at about 1 foot intervals throughout a cylindrical load of prilled ammonium nitrate 6 percent fuel oil in 'a bore hole of a coal strip mine promotes the effectiveness of the explosive. Alternating plates of an aluminum alloy and magnesium alloy placed at about 6 inch intervals throughout a bore hole and separated by coarse chips of magnesium and aluminum or their alloys aid greatly in promoting the explosive effectiveness of Ian explosive composition produced using an ammoniacal ammonium nitrate solution with these metal forms.

Various modifications can be `made in the method and device `of the present invention without departing from the spirit or scope thereof for it is understood that I limit myself only as defined in the appended claims.

I claim:

1. A method of loading a bore hole which comprises; placing a thin walled aluminum cone in said hole, said cone being nonstructurally confining of an explosive blast, said cone defining an opening at its apex, said cone having its open circular base substantially of the same size as said bore hole but being movable over the length of said bore hole and said cone having its apex pointing upward in said bore hole, adding a predetermined amount of a free-flowing explosive to said bore hole to ll said bore hole a distance of from about 1 foot to about 6 feet above said cone, placing a second said cone onto said explosive in said bore hole, said second cone also having its apex pointing upward in said bore hole, adding more of said explosive to said hole to fill said bore hole a distance of from about 1 foot to about 6 feet above said second cone, continuing the alternate additions of said cones and said explosive to said bore hole until said bore hole is filled to a predetermined height, placing an initiator onto the explosive load, and, stemming said bore hole.

2. A method of loading a bore hole which comprises; placing a perforated magnesium saucer-shaped disc in a bore hole, said disc being nonstructurally coniining of an explosive blast, the diameter of said disc being substantially the same as the diameter of said bore hole but permitting movement of said disc over the length of said bore hole, positioning said disc whereby the plane defined by the circumference of said disc is parallel to the cross-section of said bore hole and normal to the principal axis of said bore hole, adding a predetermined amount of a 50-50 mixture of coarse magnesium and aluminum chips to said bore hole to ll said bore hole a distance of from about 1 foot to about 3 feet above said disc, placing a second said magnesium saucer-shaped disc in said bore hole, adding a second predetermined amount of said 50-50 mixture of coarse magnesium and coarse aluminum chips to fill said bore hole a distance of from about 1 foot to about 3 feet above said second disc, continuing said alternate additions of said discs and said chips until said bore hole is loaded to a predetermined height, pouring a liuid ammoniacal ammonium nitrate solution over said metal in said bore hole, arming the loaded bore hole with an initiator, and, stemming said loaded hole.

3. A method for loading a bore hole which comprises:

(a) placing into a bore hole an electron conducting disc-like member having at least one plane the periphery of which is dened by a circle, said member having a maximum diameter smaller than that of the diameter of the said bore hole and said member being nonstructurally confining of an explosive blast,

(b) positioning said member so that the plane dened by the said periphery is substantially parallel to the cross section of said bore hole and substantially normal to the principal axis of said bore hole,

(c) introducing a predetermined amount of an explosive into said bore hole to ll said bore hole to a distance of from 4 inches to about 10 feet above said positioned disc,

(d) placing a second of said discs into said bore hole on top of said explosive and positioning said second disc with respect to the bore hole in the same manner as said first disc,

`( e) introducing a second predetermined amount of said explosive into said bore hole thereby to ll said bore hole a distance of about 4 inches to about 10 feet above said second disc,

(f) continuing said alternate placing and positioning of said discs and said explosive into said bore hole until said bore hole is iilled to a predetermined height,

(g) placing an initiator for said explosive into said bore hole during the loading of said hole,

(h) stemming said bore hole.

4. A method for loading a bore hole which comprises:

(a) placing an electron conducting circular disc-like member in a bore hole, said member having a diameter smaller than that of the diameter of said bore hole and said member ranging in thickness from about 0.001 inch up to about 1 inch,

(b) positioning said member whereby the plane defined by the periphery of said disc is parallel to the crosssection of said bore hole and normal to the principal axis of said bore hole,

(c) introducing a predetermined amount of an explosive into said bore hole to fill said bore hole to a distance of from one foot to six feet above said positioned disc,

(d) placing a second electron conducting circular disclike member into said bore hole on top of said explosive and positioning said second disc with respect to the bore hole in the same manner as said rst disc,

(e) introducing a second predetermined amount of said explosive into said bore hole thereby to fill said bore hole a distance of about one foot to six feet above said second disc,

(f) continuing said alternate placing and positioning of said discs and said explosive into said bore hole until said bore hole is filled to a predetermined height,

(g) placing an initiator for said explosive into the bore hole during the loading of said hole, and

(h) stemming said bore hole.

5. The process as deined in claim 4 wherein the circular disc is of a material selected from the group consisting of magnesium, aluminum, magnesium alloys and aluminum alloys.

References Cited in the le of this patent UNITED STATES PATENTS 1,767,182 Lisse June 24, 1930 2,168,030 Holmes Aug. 1, 1939 2,586,801 Epler et al Feb. 26, 1952 2,837,996 Klotz June 10, 1958 

3. A METHOD FOR LOADING A BORE HOLE WHICH COMPRISES: (A) PLACING INTO A BORE HOLE AN ELECTRON CONDUCTING DISC-LIKE MEMBER HAVING AT LEAST ONE PLANE THE PERIPHERY OF WHICH IS DEFINED BY A CIRCLE, SAID MEMBER HAVING A MAXIMUM DIAMETER SMALLER THAN THAT OF THE DIAMETER OF THE SAID BORE HOLE AND SAID MEMBER BEING NONSTRUCTURALLY CONFINING OF AN EXPLOSIVE BLAST, (B) POSITIONING SAID MEMBER SO THAT THE PLANE DEFINED BY THE SAID PERIPHERY IS SUBSTANTIALLY PARALLEL TO THE CROSS SECTION OF SAID BORE HOLE AND SUBSTANTIALLY NORMAL TO THE PRINCIPAL AXIS OF SAID BORE HOLE, (C) INTRODUCING A PREDETERMINED AMOUNT OF AN EXPLOSIVE INTO SAID BORE HOLE TO FILL SAID BORE HOLE TO A DISTANCE OF FROM 4 INCHES TO ABOUT 10 FEET ABOVE SAID POSITIONED DISC, (D) PLACING A SECOND OF SAID DISCS INTO SAID BORE HOLE ON TOP OF SAID EXPLOSIVE AND POSITIONING SAID SECOND DISC WITH RESPECT TO THE BORE HOLE IN THE SAME MANNER AS SAID FIRST DISC, (E) INTRODUCING A SECOND PREDETERMINED AMOUNT OF SAID EXPLOSIVE INTO SAID BORE HOLE THEREBY TO FILL SAID BORE HOLE A DISTANCE OF ABOUT 4 INCHES TO ABOUT 10 FEET ABOVE SAID SECOND DISC, (F) CONTINUING SAID ALTERNATE PLACING AND POSITIONING OF SAID DISCS AND SAID EXPLOSIVE INTO SAID BORE HOLE UNTIL SAID BORE HOLE IS FILLED TO A PREDETERMINED HEIGHT, (G) PLACING AN INITIATOR FOR SAID EXPLOSIVE INTO SAID BORE HOLE DURING THE LOADING OF SAID HOLE, (H) STEMMING SAID BORE HOLE. 